Mapper type convert

Ok, I had previously posted about a way to get pixel for pixel warping with the mapper, IE I want to cut out a section and then warp it a little bit, but generally have the input and output resolution the same. This came up again, using a datapath that takes a 4k connection and outputs 4x HD feeds. I am using a 4K video made of 4x HD videos so I am in perfect sync. I want to just cut out each quadrant and then on the output side tweak the geometry a bit. A few things came to mind,

1\. It would be great to allow for numeric entry into the mapper source and outputs but making perfect slices, it would also be great if these values were in pixels where top left is 0,0\. In fact I would love if Izzy had a default coordinate scheme that was pixels, not plus or minus 50 or 100, something precise and reliable and traceable to real world numbers.

2\. Converting slice types. So to get around some of this I start with a mask, then use the mask as a reference to add a grid mapper and use the snapping feature (points snap to other points) to make the grid line up with the mask. Except at the moment grids snap on the inout pane but not the output pane of the mapper. Instead it would be great to make a mask (so inout and output pixels are equal and then right click on the mask and convert to quad- do some warping and save. Even more useful, do the warping and thne think, I could fix that with a grid, righ click on the quad, convert to grid - have it keep the quad warping but now have a grid and make some tweaks, super fast workflow...

3\. To make it clear as it was stuck in the top point and I would really like this to happen- a unified coordinate systems built on pixels not random numbers!!!! Let us set any coordinate on the screen to a real world pixel value.